Question

Solve for cos2a=(3^1/2)/2

Answer 1

cos(pi/6)=sqrt{3}/2
and
cos(11pi/6)=sqrt{3}/2
so
cos(2npi+pi/6)=sqrt{3}/2
and
cos(2npi+11pi/6)=sqrt{3}/2
for n=0,1,2,...
so
2npi+pi/6=2a
and
2npi+11pi/6=2a
solve both for a

Answer 2

1/2(2npi+pi/6)=a
1/2(2npi+11pi/6)=a